At present, communication services in mobile station apparatus are widely proliferated and used by a majority of people. Communication providers, which provide the communication services as described above, cover necessary service areas by installing a number of base station apparatus (referred to as a macrocell base station apparatus) capable of wireless communication in a communication range (macrocell) of which the radius is about several hundreds of meters to several kilometers, and provide various services such as voice communication, television (TV) telephony, and packet communication.
However, it is difficult to fully cover the entire service area in only a macrocell, and there is a place of a weak electric field in the vicinity of a boundary of the macrocell or in a place in which the reception of radio waves is difficult such as indoors. In the places as described above, there is a problem in that a sufficient communication speed is not obtained and the quality of call voice is not stable. In order to cover such places, the introduction of a base station apparatus (referred to as a femtocell base station apparatus) capable of wireless communication in a communication range (femtocell) of which the radius is about several meters to several tens of meters is being studied. The femtocell base station apparatus is different from a macrocell base station apparatus, and, for example, connected to a core network (CN) installed by a communication provider using a broadband link used in an individual home. Because the burden on the communication provider is reduced by using the broadband link or the like in communication using the femtocell base station apparatus as described above, communication cost is reduced as compared to communication using the macrocell base station apparatus.
In addition, in the femtocell base station apparatus, users are limited to a minority of users permitted by a user installing the femtocell base station apparatus. That is, because the femtocell base station apparatus is used by a limited minority of mobile station apparatus, the mobile station apparatus can perform stable communication at a high speed.
Even in 3rd Generation Partnership Project (3GPP) in which third and subsequent generation communication schemes are being studied, specifications are being recommended for a home (evolved) Node B ((e)NodeB), a closed subscriber group (CSG) cell, or the like as a macrocell base station apparatus that covers a small-scale area such as a home (for example, Non-Patent Document 1).
As described above, in the femtocell, the mobile station apparatus can perform stable communication at a low cost and high speed.
On the other hand, in 3GPP, at present, Long Term Evolution-Advanced (LTE-A) is being studied as the next communication scheme of LTE. In LTE-A, there is a need to implement higher speed communication than in LTE, and support a wider band (a band of up to 100 MHz exceeding a band of 20 MHz of LTE) than in LTE.
However, it is difficult to secure a broadband continuous frequency domain for LTEA throughout the world, and it is necessary to maintain compatibility with LTE as much as possible. Carrier aggregation (CA) technology for securing a maximum bandwidth of 100 MHz and implementing high-speed and large-capacity communication by aggregating a plurality of carriers having a bandwidth of up to 20 MHz to perform communication has been proposed and agreed upon at the 3GPP radio access network (RAN) #53b meeting (Chapter 5 of Non-Patent Document 2).
In the CA technology, a carrier having a bandwidth of up to 20 MHz is referred to as a component carrier (CC). In addition, detailed specs such as signaling, channel arrangement, and mapping in CA are scheduled to be designed later, and various discussions for designing the specs are being conducted by each working group (WG) of 3GPP.
Here, if the CA technology is applied to communication in the above-described femtocell, higher-speed communication can be performed. However, there is a problem in that a signal of the femtocell is affected by interference from a signal of the macrocell in a range in which the macrocell and the femtocell overlap.
For this problem, for example, discussions on technology related to a radio layer 1 are ongoing in WG of RAN 1. In this WG, discussions on necessary types of CCs are also ongoing. For example, Non-Patent Document 3 is a contribution presented to study types of CCs. Non-Patent Document 3 discloses a frequency arrangement method to which the CA technology is applied when there is a small-size base station apparatus (femtocell base station apparatus) having a lower transmission power than a macrocell base station apparatus.
Specifically, Non-Patent Document 3 discloses the frequency arrangement method in which a macrocell base station apparatus and a femtocell base station apparatus use separate CCs. In addition, as disclosed in Non-Patent Document 3, although different CCs are normally used in a macrocell and a femtocell, the same CC is switched and used in the macrocell and the femtocell only when the CA technology is applied in the femtocell.